Re: Formal syntax for org-cite

[Timothy]

Hi All,

I've been away for a bit, but now I'm back and getting back into things
🙂. For starters, I'm thinking we may as well put a description of the
citation syntax into org-syntax. I'm still interested in more/broader
changes to improve the clarity and specificity of org-syntax (and have
had some more ideas on that front), but we may as well start by adding
this missing section.

I think my current version resolves all the comments made so far, see
below in case there's anything else that jumps out as needing changing.

The draft v3 follows:

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Citations follow the pattern
#+begin_example
[cite CITESTYLE: GLOBALPREFIX KEYCITES GLOBALSUFFIX]
#+end_example
where "cite" and =CITESTYLE=, =KEYCITES= and =GLOBALSUFFIX= are /not/
separated by whitespace. Whitespace after the leading colon or before
the closing square bracket is not significant. All other whitespace is
significant.

The only mandatory component, =KEYCITES= consists of one or more instances of 
the
following pattern, separated by semicolons,
#+begin_example
KEYPREFIX @KEY KEYSUFFIX
#+end_example
where =KEYPREFIX=, =@KEY=, and =KEYSUFFIX= are /not/ separated by whitespace.

=KEY= can be made of any word-constituent character, =-=, =.=, =:=, =?=,
=!=, =`=, ='=, =/=, =*=, =@=, =+=, =|=, =(=, =)=, ={=, =}=, =<=, =>=,
=&=, =_=, =^=, =$=, =#=, =%=, or =~=.

=KEYPREFIX= and =KEYSUFFIX= are optional and can contain any characters
other than a semicolon (=;=), so long as all square brackets are
balanced. =KEYPREFIX= cannot contain any subsequence that forms a =KEY=.

Hence, a minimal citation is formed by the pattern ~[cite:@KEY]~.

=CITESTYLE= consists of a main =STYLE= and optionally a =VARIANT=​.
Both the =STYLE= and =VARIANT= are prefixed by a forwards slash.
#+begin_example
/STYLE/VARIANT
#+end_example
=STYLE= and =VARIANT= can be made of any alphanumeric character, =_=, or
=-=​. Additionally, =VARIANT= can itself contain forward slashes (=/=) .

=GLOBALPREFIX= and =GLOBALSUFFIX= can contain the same characters as
=KEYPREFIX= and =KEYSUFFIX=. In the same manner as instances of the
=KEYCITES= pattern, =KEYCITES=, =GLOBALPREFIX=, and =GLOBALSUFFIX= must
be separated by semicolons.

------

Let me know if this looks alright.

All the best,
Timothy.